The present innovation relates to a centrifugation chamber. Such a centrifugation chamber is used preferably for testing liquid (cerebrospinal fluid). In the cytological testing of such fluids the problem is that there are in the fluid to be tested only relatively few cells that constitute the test object. It is crucial, therefore, to produce a sediment of the cells with a slide, with little loss of cell material in this process as well as in the subsequent processes, as e.g. staining of the sediment sample or fixing of the sediment sample.
In the past, a number of centrifugation chambers have been proposed.
Such a known centrifugation chamber consists of an upper part, which is designed in the manner of a tubule, and which is filled with the liquid to be tested.
This upper part is pressed under the load of a weight onto a lower part, a slide being placed on the bottom surface of the lower part. Between the slide and the upper part is a filter paper or other sorption material. In the following, this sorption material is referred to as filter paper, to simplify matters.
In the area of the circular opening for placing the upper part on the slide, the filter paper is cut out circularly, and this with a diameter such that the sealing edge of the upper part sits on an annular zone of the filter material. As a result, the liquid to be tested, with which the upper part is filled, stands on the slide in the manner of a liquid column, covering an annulus-shaped zone of the filter material as well.
For the sedimentation of the cells to be tested, a so-called spontaneous sedimentation is employed, that is, the centrifugation chamber filled with the test fluid is left standing still for a certain period of time, so that the heavier cell components sink to the bottom in the suspension by gravity and deposit on the circular zone of the slide.
Then the contact pressure of the upper part against the lower part is reduced, so that over the sedimented sample the remaining residual fluid has easier access to the filter material, which filter material absorbs the fluid until the filter material is saturated and the sedimentation field is free of test fluid.
Such a centrifugation chamber has proved successful, but has the disadvantage that because of the spontaneous sedimentation only little cell precipitate is obtainable, and also the sedimentation requires a long period of time.
Another major disadvantage of the known centrifugation chamber is that one cannot combine different size upper parts that can be filled with different volumes of fluid with always the same lower part. The usability of such a centrifugation chamber is thus limited. Besides, the retention of the filter material on the slide is insufficiently solved, in that on the one hand the filter material may slip as the centrifugation chamber is being closed, that is, as the upper part is being clamped on the lower part, and secondly the filter material is not reusable.